Added allowMultiline property to the jsx-curly-spacing rule

[mathieumg]

What do you think about this? I had hoped it would be like that by default when I first read about that rule being introduced! Which prompts my next question: should allowMultiline be on by default? I currently put it off by default and I'm ignoring it when the option is set to "always" as to not break current users (new warnings/errors) that do:

<Hello name={
  firstname
} />;

using

"jsx-curly-spacing": [2, "always"]

If it were on by default, I could leverage the option in all cases, meaning users would have a way to enforce:

// Valid
<Hello name={ firstname } />;

// Invalid
<Hello name={
  firstname
} />;

with

"jsx-curly-spacing": [2, "always", {"allowMultiline": false}]

However, current users relying on

<Hello name={
  firstname
} />;

to warn with the current defaults, would not be warned anymore.

[yannickcr]

Thanks for this!

I think it's ok to make a small break on this rule to make it more flexible.

[mathieumg]

So, which break is it? 😛 Default to true, but rule also considered with "always" if set to false? (Last example I showed)

If so, I'll update the PR!

[moll]

👍 This would then match http://eslint.org/docs/rules/object-curly-spacing.html which allows multilines in the never setting.

[yannickcr]

So, which break is it? 😛 Default to true, but rule also considered with "always" if set to false? (Last example I showed)

Yep, that break ;)

[mathieumg]

Refactored this part a bit because it was getting hard to follow! I don't know what your stance is on early returns to avoid deep nesting, but I can change this to an else statement if that is what you prefer.

[yannickcr]

LGTM